Carburetor



w. H. WEBER CARBURETOR Nov. 4,1941.

Fil ed May 22, 1939 ATTORNEY Patented Nov. 4, 1941 OABBURETOR' Walter H.Weber, Detroit, Mich assignor to Detroit Lubrlcator Company, Detroit,Mich a corporation of Michigan Application May 22, 1939, Serial No.274,882

5 Claims.

My invention relates to new and useful im- 7 movements in carburetorsand more particularly toe. carburetor for supplying fuel mixture for aninternal combustion engine.

An object of my invention is to provide a carburetor which is operableto lift fuel from a low lever supply tank, thereby eliminating theneces-,

sity for the usual vacuum tank or fuel feeding pump.

Another object is to provide, a carburetor in which the fuel and airsupplied to the engine will be uniformly mixed.

Another object is to provide means to supplemental fuel foracceleration.

Another object is to provide means for increasing the ratio of fuel toair for engine starting and for cold engine operation.

The invention consists in the improved construction and combination ofparts, to be more fully described hereinafter and the novelty of whichwill be particularly pointed out and distinctly claimed.

In the accompanying drawing, to be taken as a part of thisspecification, I have fully and clearly illustrated a preferredembodiment of my invention, in which drawing- 7 Figure 1 is a view invertical central section of a carburetor showing my invention, and

Fig. 2 is a top plan view of the carburetor of Fig. 1 but having the airinlet valve broken away to show the internal construction.

Referring to the drawing by characters of reference, i designatesgenerally the carburetor casing having a vertical passageway theresupplythrough with an open upper end portion 2 providing an air inlet'chambert. Opening downward from the chamber 8 eccentrically thereof,

there is a mixing chamber a which discharges through a throttle bodymember 5 having a flange t by which the carburetor may be secured to theinlet manifold of the engine. Within the throttle body member 5 there isa butterfly type throttle valve '7 rotatably supported by a throttleshaft 8. Positioned at one side of the mixingchamber a there is avertically extending cylindrical dash-pot and pump chamber a whichiseccentric of but directly beneath the air inlet 3. The chamber 9 isseparated from the air inlet 3 by a horizontally extending wall it whichhas therein a cylindrical recess ll opening downward into andconcentrically with the chamber 9. A guideway it extends concentricallyfrom the upper end of the recess il through the wall it to the air inlet3. Reciprocally guided and fitting in the guideway ii there is a valvestem I3 which ex- 55' tends at its upper end into the inlet 3 and haspivotally secured thereto a link 14. Within the air inlets andcontrolling admission of air to the I mixing chamber 4, there is e.suction responsive air valve plate I5 which is eccentrically mounted ona shaft It to swing downward across the entrance to the mixing chamber4. The link M is pivotally secured toa. bracket l1 secured to theunderside of the plate It on the opposite side of shaft lBfrom thechamber 5 so that the valve stem. It will be lifted on opening movementof the air valve. A supporting member i8 projects from the wall' I0 intothe mixing chamber A and has a vertical bore i9 therethrough concentricwith the longitudinal axis of the mixing chamber. Tightly fitting andsecured within the bore is there is a nozzle member 26 which extendsdownward therefrcm- The nozzle member 26 has a converging-divergingVenturi-like bore providing a throat 2i positioned within the length ofbore is. The throat preferably comprises a short downward flaringportion of greater included angle than the diverging discharge portion22 of the nozzle member so that the throat entrance from the convergingair inlet portion 23 of the bore will be the most restricted portion ofthe nozzle bore. Supported by the casing i there is a float chambermember it having a constant level reservoir 25 with a fuel inlet 26 fromthe usual supply tank. The inlet 25 is controlled by the usual floatoperated valve mechanism 27 which serves to maintain the liquidlevelsubstantially constant at say the line L-L. The reservoir 25 isprovided with a calibrated air inlet to from atmosphere, the reservoirbeing otherwise sealed against air admission. A fuel supply conduit 29leads from the bottom of the float chamber into the lower end of thedash pot chamber 9. Reciprocal in the wall recess ii there is atubularvalve port member so having at its upper end a restricted por- 1tion at providing a valve port. The, lower end portion 32 of member 30is of enlarged internal diameter and extends downward into the chamber9.. The upper portion of member 30 is provided with an external rackcooperable with a pinion 33 for reciprocating the member 80.Reciprocally fitting within the tubular portion 82, there is a sleevemember 33 having a flange 8d at its lower end on which seats an annularcupshaped piston 35. The tubular valve port member 30 is urged upwardand the piston 35 is opposed in upward movement by a helical coil spring38 which surrounds the sleeve member 83 and the lower tubular portion 32and which abuts a spring seat member "secured to and extending laterallyfrom the portion 32. Intermediate the ends of the valve stem is there isa metering valve 38 cooperable with and extending through the port It.The lower end portion of the stem I I is secured as by a cross pin is ina spider 4| rigidly fixed within the sleeve member 83 Leading from therecess ii at its upper end and on the outlet side of port ll there is afuel conduit 4| which opens into the bore I! for communication with acalibrated orifice 42 which opens into the throat 2i. A vapor conveyingconduit 48 for gas and air extends through the wall I. from thereservoir 25 above the liquid level therein.

The conduit 43 has a calibrated opening 44 into the reservoir 26 whichis proportioned relative to the calibration of the atmospheric bleed 28so as to control the sub-atmospheric pressure or depression over theliquid in the reservoir.- The other end of-conduit 43 opens into thebore I! above the conduit 4| and communicates with a calibrated orifice45 which opens into the throat 2i directly above and on the air inletside of the orifice 42 so that any discharge from the orifice 45 willpass directly overuan'd across the outlet of orifice 42. The conduit 43communicates through a supplemental fuel conduit 48 with the dash-potchamber 9 but out of direct communication with the main fuel conduitthrough the sleeve 33 and portion 32; that is, the conduit 48 opens intothe annular pump chamber above the piston 35 and surrounding the lowerend portion of the valve port member 80. The conduit 48 is provided witha downward seating ball check valve 41 having sufiflcient weight to holdthe conduit 46 closed against discharge of fuel by suction in theconduit 43.

The operation of this carburetor is as follows: When starting a coldengine the pinion 33 will be rotated to move the port member 3 downwardagainst the force of spring 36, thereby increasing the opening of theport 3i. This ad- Justment will increase the resistance to openingmovement of air valve. it by increasing the compression on the spring86, thereby reducing the air supplied for a given sub-atmosphericpressure in the mixing chamber t and will also in crease the effectivefiow area of the fuel supply conduit through orifice M to furtherincrease the ratio of fuel to air for all positions of the air valve l6. When the engine has fired and is running under its own power, thepinion tit will be rotated to return the valve port member 30 towardnormal operating position and completely to normal position when theengine is thoroughly warmed up. The sub-atmospheric pressure in themixing chamber 6 will not only act on orifice 42 to draw fuel from thereservoir ill but will also act through conduit 3 to reduce the pressureover the liquid in the reservoir so that fuel will be lifted from thesupply tank and drawn into the reservoir when the float mechanism opensthe inlet passageway 26. The air and gas drawn into the throat itthrough orifice 45 will discharge directly over the fuel orifice 42,thereby aiding the feeding of fuel into the nozzle member by aspiratingaction. This air and gas will also be discharging directly into the fuelfrom orifice 42 due to the throat flare and the main air stream passingthe throat so that the liquid fuel will be broken up and intimatelymixed with the air in the nozzle member, The air bleed 28 provides adifferential of pressure above and below the fuel so that fuel will feedthrough the port or orifice 42. During idling operation of the enginethe air valve ll will remain in substantially closed position so thatthe nozzle member 20 will have very little boosting effect by Venturiaction. As the throttle 'l is opened, increasing the sub-atmosphericpressure in the mixing chamber 4 and on the outlet side of air valve II,the valve II will move toward open position in accordance with thesub-atmospheric pressure and the resistance afforded by the spring 38and will lift the fuel metering valve relative to port II to increasethe fuel supplied relative to the increased supply of air. As the airvalve moves toward open position, increasing the rate of air flowthrough the carburetor, the nozzle member will become effective to boostthe suction over the liquid in the reservoir on the fuel orifice 42. Ifthe throttle valve 1 is moved quickly toward open position for engineacceleration, the fuel in the annular pump chamber will be compressed bythe piston II and be discharged through conduit 4| into the vaporconveying conduit 43 and thence be discharged through orifice 45 intothe bore of nozzle member 20, thus providing the necessary enrichedmixture for quick acceleration.

By positioning the nozzle member 2| on the outlet side of air valve l 5such that the air valve controls the air supply to the nozzle memberinlet 23, the disadvantage of frost forming in the throat of the nozzlemember is eliminated. The forn: tion of frost in the throat of a nozzlemember \hich passes or upplies substantially all of the air for lowspeed or engine idling operation will obstruct the fuel orifice andseriously impair carburetor operation. The high air velocity through thenozzle member at low e'ngine speeds is avoided by my constructionwherein only a portion of the airat low speeds passes through the nozzlemember, the, remaining air passing around the nozzle member and mixingzvth the fuel discharging from the nozzle mem- It will be apparent thatthis carburetor can also be used as a gravity feed carburetor or onehaving the float chamber fed by means of a vac uum tank or fuel pump. Ifit is desired to'so utilize the carburetor, it is only necessary toincrease the size of bleed 23 so that substantially atmospheric air willexist over the fuel in th reservoir 25.

What I claim and desire to secure by Letters Patent of the United Statesis:

l. A carburetor comprising, a casing having a passageway therethroughwith an air inlet and a fuel mixture outlet, a nozzle member having aconverging-diverging bore providing a throat, said bore having one endopen for air admission and having its other end discharging into saidpassageway, a fuel reservoir, a fuel supply conduit leading from saidreservoir and discharging into said bore at said throat, a vaporconveying conduit leading from said reservoir above the liquid leveltherein and discharging into said bore at said throat, the point ofdischarge of said fuel conduit being substantially at,the point of lowpressure in the discharge path of vapor from said vapor conduit, theopening of said vapor conduit into said bore being on the air admissionside of and closely adjacent the open ing of said fuel conduit into saidbore so that the vapor is discharged acrossv the fuel conduit opening toincrease the suction effect on said fuel opening and to thoroughly blendthe vapor and fuel in said bore, a supplemental fuel supply conduitleading from said fuel conduit into said vapor conduit, and meanstocontrol the discharge'of fuel through said supplemental conduit,

to said bore.

2. A carburetor comprising, a casing having a passageway therethroughwith an air inlet and a fuel mixture outlet, a nozzle member having aconverging-diverging bore providing ,a throat, said bore having one endopen for air admission and having its, other end discharginginto saidpassageway, a fuel reservoir, a fuel supply conduit leading from saidreservoir and discharging into said bore at said throat, a vaporconveying conduit leading from said reservoir above the liquid leveltherein and discharging into said bore at said throat, the pointof'discharge of said fuel conduit beingsubstantially at the point of lowpressure in the discharge path of vapor from said vapor conduit, theopening of said vapor side of and closely adjacent the opening of saidfuel conduit into said bore so that the vapor is discharged across thefuel conduit opening to increase the suction effect on said fuel openingand to thoroughly blend the vapor and fuel in said bore, a supplementalfuel supply conduit leading from said fuel conduit into said vaporconduit, a pump operable to discharge fuel through said supplementalconduit to said bore, and an automatic valve in and closing saidsupplemental conduit against feeding of fuel by pressure reduction insaid vapor conduit.

3; A down-draft fuel-lifting carburetor com prising, a casing having anopen-ended passageway therethrough with an air inlet at its upper endand a fuel mixture outlet at its lower end, "an eccentrically mountedvalve plate in said air inlet and responsive to suction in-saidpassageway, said valve plate being cooperable with said air inlet uponmovement to admit air to said passageway along its peripheral surface, adownfrom the side walls of said'passageway on the outlet side of saidvalve plate, said nozzle memher having an open-endedconverging-diverging bore providing a throat, a fuel reservoir, a vaporconveying conduit leading from said reservoir above the liquid leveltherein and opening lat- 'erally into said throat, a fuel conveyingconduit leading from saidreservoir below the liquid level therein andopening laterally into said throat closely adjacent to and below theopening of said vapor conduit, a pump chamber in said fuel conduit. atubular valve port member reciprocally fitting in said fuel conduit'andhaving a portion extending into said pump chamber, a sleeve member insaidipump chamber and reciprocally fitting said extending portion, apiston carried by said sleeve member and fitting said chamber.

a fuel metering rod extending through said port member andinterconnecting said valve plate and said sleeve member, a helical coilspring sur-' rounding said sleeve member and interposed between saidtubular member and said piston to oppose movement of said piston andsaid valve plate, and means to adjust said port member to regulate theeifective flow area of said fuel conduit.

4. A down-draft carburetor comprising, a casing having a tubular airinlet portion at its upper end, a mixing chamber passageway and adash-pot chamber having substantially parallel longitudinal axes, saidmixing chamber passageway opening downward from and eccentric of saidinlet portion, said dash-pot chamber being positioned'besides saidmixing chamber passageway and directly below said inlet portion, alaterally extending wall in said casing separating said dash-pot chamberfrom said inletportion and havingan elongated recess opening into saiddash-pot chamber, said wall having a guideway extending concentricallyfromsaid recess and opening into said inlet portion, the longitudinalaxes of said recess and said guideway being substantiallyparallel to theaxes of said 'mixing chamber passageway and said dash-potchamber, avalve stem extending through said guideway into said dash-pot chamberand said inlet portion and having a metering valve intermediate itsends, an eccentrically mounted valve plate in said inlet portion andconnected to said stem,"

an open-ended downwardly discharging nozzle member extendinglongitudinally of and spaced fromthe walls of said passageway andsupported by said wall,.thelongitudinal axis of said nozzle -i saiddash-pot chamber and connected .to said valve stem, a valve port memberin said recess. and surrounding said metering valve, and means to supplyfuel to said dash-pot chamber.

5. A carburetor comprising, a casing-having a passageway therethroughwith an air inlet and a fuel mixture outlet, a nozzle member having 'aconverging-divergingbore providing a throat,

' charging into said bore at said throat, means to supply a .gas to saidreservoir, a gas and vapor conveying-conduit leading from said reservoirabove the liquid level therein and discharging into said bore at saidthroat, the longitudinal axis of said vapor conduit being at an anglerelative to the longitudinal axis of said fuel conduit, said axesintersecting within said bore closely adjacent the opening of said fuelconduit into said bore, the opening'of said vapor conduit into said borebeing on the air admission side ofand closely adjacent the opening ofsaid 7 "fuel in said bore.

WALTER H. WEBER;

